Delirium tremens (colloquially, the DTs, "the horrors", "the shakes" or "rum fits;" literally, "shaking delirium" or "trembling madness" in Latin) is an acute episode of delirium that is usually caused by withdrawal or abstinence, from alcohol following habitual excessive drinking, or benzodiazepines or barbiturates (and other minor tranquilizers). Delirium tremens can also appear after a rapid reduction in the amount of alcohol being consumed by heavy drinkers, or a rapid reduction of intake of benzodiazepines or barbiturates. Caused by alcohol, it only occurs in individuals with a history of constant, long-term alcohol consumption. Occurrence due to benzodiazepine or barbiturate withdrawal does not require as long a period of consistent intake of such drugs. Prior use of both tranquilizers and alcohol can compound the symptoms, and while extremely rare, is the most dangerous especially if untreated. Barbiturates are generally accepted as being extremely dangerous, both due to overdose potential and addiction potential including the extreme withdrawal syndrome that usually is marked by delirium tremens upon discontinuation. Due to this, barbiturates are rarely used ambulatory anymore, being replaced by the generally accepted less dangerous benzodiazepines, which however still cause a similar withdrawal syndrome.

Five percent of acute ethanol withdrawal cases progress to delirium tremens[1]. Unlike the withdrawal syndrome associated with opiate addiction (generally), delirium tremens (and alcohol withdrawal in general) can be fatal. Mortality can be up to 35% if untreated; if treated early, death rates range from 5-15%.[2]

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The main symptoms are confusion, disorientation and agitation. Other common symptoms include intense hallucinations such as visions of insects, snakes or rats (or stereotypically, pink elephants). These may be related to the environment, e.g., drawings on wallpaper that the patient would perceive as giant spiders attacking him or her. Unlike hallucinations associated with schizophrenia, delirium tremens hallucinations are primarily visual, but associated with tactile hallucinations such as sensations of something crawling on the subject - a phenomenon known as formication. Delirium tremens can sometimes be associated with severe, uncontrollable tremors of the extremities and secondary symptoms such as anxiety, panic attacks and paranoia.

Delirium tremens (DT) should be distinguished from alcoholic hallucinosis, the latter occurring in approximately 20% of hospitalized alcoholics and not carrying a significant mortality. In contrast, DT occurs in 5-10% of alcohol-dependent people and carries up to 5% mortality with treatment and up to 35% mortality without treatment. [3] DT is characterized by the presence of altered sensorium; that is, a complete hallucination without any recognition of the real world. DT has extreme autonomic hyperactivity (high pulse, blood pressure, and rate of breathing), and 35-60% of patients have a fever. Some individuals experience seizures as well.

Delirium tremens can occur after a period of heavy alcohol drinking, especially when the person does not eat enough food.
It may also be triggered by head injury, infection, or illness in people with a history of heavy use of alcohol.

It is most common in people who have a history of alcohol withdrawal, especially in those who drink the equivalent of 7 - 8 pints of beer (or 1 pint of "hard" alcohol) every day for several months. Delirium tremens also commonly affects those with a history of habitual alcohol use or alcoholism that has existed for more than 10 years.

The exact pharmacology of ethanol is not fully understood: however, it is theorized that delirium tremens is caused by the effect of alcohol on the benzodiazepine-GABAA-chloride receptor complex for the inhibitory neurotransmitter GABA. Constant consumption of alcoholic beverages (and the consequent chronic sedation) causes a counterregulatory response in the brain in attempt to re-achieve homeostasis.

This is all made worse by excitatory neurotransmitter upregulation, so not only is sympathetic nervous system over-activity unopposed by GABA, there is also more of the serotonin, norepinephrine, dopamine, epinephrine, and particularly glutamate. Excitory NMDA receptors are also upregulated, contributing to the delirium and neurotoxicity (by excitotoxicity) of withdrawal. Direct measurements of central norepinephrine and its metabolites is in direct correlation to the severity of the alcohol withdrawal syndrome.

Pharmacotherapy is symptomatic and supportive. Typically the patient is kept sedated with benzodiazepines, such as diazepam (Valium), lorazepam (Ativan) or oxazepam (Serax) and in extreme cases low-levels of antipsychotics, such as haloperidol until symptoms subside. Acamprosate is often used to augment treatment, and is then carried on into long term use to reduce the risk of relapse. If status epilepticus is present, seizures are treated accordingly.
Controlling environmental stimuli can also be helpful, such as a well-lit but relaxing environment to minimise visual misinterpretations such as the visual hallucinations mentioned above.